High-frequency welded finned tubes are enhanced heat transfer elements manufactured using high-frequency induction welding technology. The core lies in generating instantaneous high temperatures at the contact interface between the base tube and fins through a high-frequency electromagnetic field, achieving metallurgical bonding under pressure, thereby significantly improving heat transfer efficiency and structural reliability.

 

High-frequency welded finned tube technology utilizes a high-frequency power supply with a frequency range of 15kHz to 500kHz. An induction coil generates an alternating electromagnetic field, causing eddy currents on the surface of metal base tubes (such as carbon steel or stainless steel seamless tubes) to rapidly heat up to a plastic state (approximately 800°C–1200°C). Simultaneously, pre-formed metal fin strips (commonly low-carbon steel or aluminum strips) are pressed against the base tube under mechanical pressure, and metal atoms at the interface form a solder-free molten connection through diffusion. The weld strength of this metallurgical bond can reach over 90% of the base material strength, with a thermal resistance below 0.0005㎡·K/W. This effectively solves problems such as high thermal resistance and easy loosening of fins in traditional wound finned tubes, greatly improving heat transfer efficiency and equipment reliability.

 

The manufacturing process mainly includes four stages:

1. Base Tube Pretreatment: The base tube undergoes acid pickling for rust removal, degreasing, and phosphating treatment to form a 5–10μm phosphate protective film, enhancing welding adhesion and corrosion resistance;

2. Fin Forming and Wrapping: The fin strip is rolled into a spiral shape (L-type or U-type cross-section) and wound around the outer wall of the base tube with precisely controlled pitch (deviation ≤0.2mm);

3. High-Frequency Welding: An induction coil the joint for localized heating, while applying a radial pressure of 5–30MPa. The welding speed is typically 1–30 meters per minute, requiring strict control of current (50–80A), temperature (±5°C), and time (0.1–1 second) to prevent cold welding or deformation;

4. Cooling and Shaping: Spray or immersion cooling (rate 50–80°C/second) is used to rapidly solidify the weld, avoiding stress concentration or fin deformation.

 

High-frequency welded finned tubes offer the combined advantages of high heat transfer efficiency, strong structural stability, and good corrosion resistance. Their fin spacing can be controlled within the range of 3–15mm, with welding uniformity error below 5%. Such elements are widely used in industrial heat exchangers, power equipment cooling systems, chemical waste heat recovery units, and civilian heating equipment, serving as core components for efficient thermal energy transfer.